ES2672570T3 - Device for unmolding parts - Google Patents

Abstract

Device for unmolding parts in a mold, comprising a skate (1) comprising a slide (8) to accommodate a forming insert (2) to mold a recess of the piece to be molded, said slide (8) being associated in a way oblique with a push rod (9), which can move said slide (8) to an ejection position to eject a piece to be molded, said skate (1) comprising a base (3) on which said slide (8) is slides along guides (23) of said base (3) that are complementary to the grooves (24) of said slide (8), wherein said push rod (9) comprises at the upper end thereof a rack (21) that meshes directly with another rack (22) of said slide (8), the movement of said push rod (9) being transferred to said slide (8) through said zippers (21, 22).

Description

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DESCRIPTION

Device for unmolding parts

The present invention relates to a device for unmolding parts, which houses a forming insert that forms recesses in injection molds. It refers to a device intended to replace the current inclined skates.

Background of the invention

In the current field of injection molds, mainly those of a considerable size (that is, molds for the automotive sector, or the like) and to obtain molded parts of plastic, whose configuration has recesses that cannot be molded by means of the system of Conventional extraction, the use of skates that have an angular movement associated with the mold is required, so that the demolding of these negative parts during the extraction procedure is facilitated.

Normally and depending on the recess to be molded, the trajectory of these skates does not have to be the same as the trajectory of the ejectors that unmold the corresponding piece. For this reason, most of these molds require the use of a double set of ejection plates.

These expulsion plates use the same movement of movement for the two groups of expulsion plates, but by means of duly incorporated mechanisms, the present invention allows, after a certain path, the first group of expulsion plates to remain stationary, while the second group continues to move to the limit of the path necessary for the total extraction of the molded part.

The first group of expulsion plates normally incorporates all the angular movement mechanisms, while the second group of expulsion plates incorporates all the ejectors that make possible the complete expulsion of the corresponding molded product.

This system, motivated mainly by the effort required to drive one or several angular elements of demoulding, requires properly sized ejection plates.

As they are angular movement mechanisms, the space required for installation in many cases forces us to look for more or less cumbersome alternatives due to the space needed to reinforce the efforts required in each case. Consequently, global dimensions of the mold of larger dimensions are required, with the consequent material costs and machining hours. In many cases, a larger capacity injection machine is also necessary, only for the dimensions of the mold, not for the weight of the piece.

All this significantly increases the cost of the mold, and often also the machines that make machining possible, which must be adapted to these needs.

Being large molds, these recessed parts normally also occupy an important part of the shape to be molded, and in these cases the incorporation of cooling elements is essential to accelerate the cooling of the molded mass by injection of molten plastic.

Therefore, the piece to be demoulded must be cooled before the expulsion procedure, since at the time of injection the material enters the mold cavity in a semi-chaste state, and to be expelled through the ejectors the material must be cold and rigid.

The process of cooling in plastic molds is achieved by internal circuits mechanized in the mold, through which cold water circulates, thus achieving a thermal jump that accelerates the hardening of the molded part.

To solve these problems, the device described in document ES 2398793 A1, of the same holder as the present application, was designed.

The purpose of the device according to the present invention with respect to the device described in said document is to reduce the volume of the device, so that it does not take up much space when assembled inside the mold.

Document DE 10128875 A1 discloses a mechanism for unmolding a recess in the molded lower housing of a vehicle incorporating two zippers that are driven by a toothed shaft.

GB 1381114 A discloses a mechanical transmission coupling for transmitting rectilinear force and movement, in which the axially movable members are located at right angles to each other and each one carries teeth inclined obliquely to the axis of the member, the members being coupled in a manner sliding in grooves in a guide member with its inter-coupled teeth, so that the axial movement of the member causes the axial movement of the other member.

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Document CN103448217 A discloses an oblique core traction demoulding device for driving helical racks. The oblique core traction release device for driving helical racks comprises an oblique core traction block, an ejecting rod, a front push rod, a rear push rod, a core traction guide block, a block of guide of expulsion rod and a block of fixed connection.

Description of the invention

The objects of the invention are achieved by the device according to the attached claim 1. Preferred embodiments are disclosed in the dependent claims. The device for unmolding parts of the invention solves the aforementioned drawbacks, presenting other advantages that will be described below.

The device for unmolding parts in a mold according to the present invention comprises a skate comprising a slide for accommodating a forming insert for molding a recess of the piece to be molded, said slide being obliquely associated with a push rod, said slider can be moved to an ejection position to eject a piece to be molded, and said push rod comprises at its upper end a rack, which meshes with another rack of said slide, the movement of said push rod being transferred to said slide to through said zippers.

Said skate comprises a base on which said slide slides along guides of said base complementary with grooves of said slide.

Preferably, said guides are placed inclined with respect to the longitudinal axis of said base, and are placed in a hole of said base, in which said slide is housed.

In addition, said slide is also preferably positioned inclined with respect to said push rod.

According to a preferred embodiment, said slide rack is positioned with its teeth perpendicular to the longitudinal axis of the slide, and the teeth of said rack of the push rod are positioned perpendicular or inclined with respect to the longitudinal axis of the rod of push.

Preferably, said push rod comprises a magnet associated with a magnetic detector to detect the position of the push rod.

The device for unmolding parts in a mold according to the present invention makes it possible to reduce the volume with respect to the device described in the aforementioned document, so that it does not take up much space when assembled within the shape of the mold.

Brief description of the drawings

For a better understanding of the above, drawings are attached in which, schematically and only by way of non-limiting example, a practical embodiment is represented.

Figure 1 is an exploded perspective view of the device for unmolding parts according to the present invention; Y

Figure 2 is a schematic elevational view of the device for unmolding parts of the present invention. Description of a preferred embodiment

First, it should be noted that the device for unmolding parts of the present invention is designed for use in large molds, for example, in molds of more than 800 kg, such as, in a non-limiting example, for automobile panels, for car doors or roofs, large appliances, etc. in which it is necessary to make interior recesses.

Said device for unmolding parts of the present invention comprises a skate 1 provided in its upper part with a base 3 on which a slide 8 slides. Said base 3 is attached to the mold by means of fixing screws.

Said device also comprises a forming insert 2 removably fixed on said slide 8 by means of screws 20, whose insert 2 molds a recess or projection in the desired shape. Obviously, said insert 2 can be removed and a different insert placed to mold a piece with a different inner projection.

Said insert 2 is the element in which the shape of the recess to be reproduced in the plastic part is machined. This insert 2 can incorporate the most suitable cooling circuit to its geometry, to optimize the cooling speed of the piece to be molded to the maximum.

It should be noted that in the molds called small molds in the molding technique, the inserts are attached laterally to the slide, that is, the insert is placed next to the skate and not on said skate. To allow a person skilled in the art to identify the mold as a large mold, this document will

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indicates that the insert is placed or fixed on the skate.

Skate 1 of the device of the present invention also comprises a push rod 9 located substantially vertically in the mold. Said push rod 9 moves said insert 2 between a closed position and an open or ejected position of the mold.

As can be seen in Figure 2, said slide 8 is positioned obliquely with respect to the push rod 9.

In accordance with the present invention, said push rod 9 comprises at its upper end a rack 21, which meshes with another rack 22 of said slide 8, the movement of said push rod 9 being transferred to said slide 8 through said zippers 21.22.

Due to the oblique arrangement of said slide 8 with respect to the push rod 9, said zippers 21, 22 move relative to each other with different angles, which allows divergent movements to be made in the direction of their sliding.

The slide 8 slides along guides 23 of said base 3 complementary with grooves 24 of said slide 8. Said guides 23 are positioned inclined with respect to the longitudinal axis of said base 3 and in a hole 26 of said base 3 , in which said slider 8 is housed.

One of the zippers 21 acts as a driving rack, since it is coupled to the ejection plate (not shown in the drawings) of the mold, driving the ejection movement. The other rack 22 moves freely, so that this rack 22 moves along said guides 23 by the drive of the drive rack 21, converting the vertical movement of the rack 21 into an angular movement.

The combination of the mechanized teeth of the zippers 21, 22 determines the divergent operating angles that must be applied in each case according to the recesses of the moldings that the current form to be molded may require.

As can be seen in the figures, the rack 22 of the slide 8 is positioned with its teeth perpendicular to the longitudinal axis of the slide 8, while the teeth of the drive rack 21 of the push rod 9 are positioned perpendicular or inclined with respect to to the longitudinal axis of the push rod 9.

In this way, for moldings perpendicular to the opening and closing movement of the mold, the teeth of the drive rack 21 will be positioned perpendicular with respect to the longitudinal axis of the push rod 9 or to the ejection movement, while those of the other rack 22 will have a corresponding inclination to ensure a perfect sliding coupling.

For demoulds with angles outside the perpendicular with respect to the opening and closing movement of the mold, the teeth of the drive rack 21 will be positioned with the necessary release angle for each case, while those of the other rack 22 will also have an inclination corresponding to guarantee a perfect sliding coupling, but by adding or subtracting the same degrees that the demolding angle deviates from the perpendicular.

In addition, said push rod 9 also comprises a magnet 27 associated with a magnetic detector 25 to detect the position of the push rod 9.

Claims (7)

5 10 fifteen twenty 25 1. Device for unmolding parts in a mold, comprising a skate (1) comprising a slide (8) to accommodate a forming insert (2) to mold a recess of the piece to be molded, said slide (8) being associated obliquely with a pushrod (9), which can move said slide (8) to an ejection position to eject a piece to be molded, said skate (1) comprising a base (3) on which said slide (8) ) slides along guides (23) of said base (3) that are complementary to the grooves (24) of said slide (8), in which said push rod (9) comprises at the upper end of the same a rack (21) that meshes directly with another rack (22) of said slide (8), the movement of said push rod (9) being transferred to said slide (8) through said zippers (21,22). 2. Device for unmolding parts in a mold according to claim 1, wherein said guides (23) are positioned inclined with respect to the longitudinal axis of said base (3). 3. Device for unmolding parts in a mold according to claim 1 or 2, wherein said guides (23) are placed in a hole (26) of said base (3), in which said slide (8) is housed ). 4. Device for unmolding parts in a mold according to claim 1, wherein said slide (8) is positioned inclined with respect to said push rod (9). 5. Device for unmolding parts in a mold according to claim 1 or 4, wherein said rack (22) of the slide (8) is positioned with its teeth perpendicular to the longitudinal axis of the slide (8). 6. Device for unmolding parts in a mold according to claim 1, wherein the teeth of said rack (21) of the pushrod (9) are placed perpendicular or inclined with respect to the longitudinal axis of the rod (9 ) of thrust. 7. Device for unmolding parts in a mold according to claim 1, wherein said push rod (9) comprises a magnet (27) associated with a magnetic detector (25) to detect the position of the rod (9) of thrust.